De nombreux antigènes de tumeur ont été identifiés depuis la découverte du premier antigène de tumeur humain il y a une vingtaine d’années, et plusieurs d’entre eux ont été utilisés comme antigène cible pour l’élaboration de vaccins thérapeutiques anti-Cancer. Cependant, les résultats des essais cliniques visant à évaluer l’efficacité de ces vaccins se sont la plupart du temps révélés décevants. Aussi, il reste indispensable d’identifier de nouveaux antigènes de tumeur cibles capables d’induire des réponses anti-Tumorales fortes et durables. Parmi les antigènes de tumeur considérés comme cibles potentielles pour un vaccin anti-Tumoral se trouve la Cycline B1, une protéine endogène impliquée dans la régulation du cycle cellulaire. Normalement exprimée de façon transitoire dans les cellules saines en division, cette protéine est surexprimée dans diverses tumeurs et est indispensable au développement tumoral. De plus, des réponses immunitaires spontanées spécifiques de cette protéine ont été observées chez des patients atteints de cancer. L’objectif de ma thèse était de caractériser la réponse en lymphocytes T CD4+, qui jouent un rôle capital dans la réponse immunitaire anti-Tumorale, spécifique de la Cycline B1 humaine chez des sujets sains et chez des patients atteints de cancer. Nous avons mis en évidence l’existence, chez des individus sains, de deux populations de lymphocytes T CD4+ préexistants spécifiques de cette protéine, à savoir des lymphocytes T CD4+ naïfs et des lymphocytes T CD4+ mémoires, cette seconde population lymphocytaire se retrouvant également chez des patients atteints de cancer. De multiples épitopes T CD4+ ont été identifiés dans cette protéine, et étaient différemment reconnus par ces deux populations de lymphocytes T CD4+. En outre, des anticorps IgG anti-Cycline B1 ont été détectés chez des patients atteints de cancer comme chez des individus sains, sans différence significative dans les taux d’anticorps entre ces deux catégories de sujets. Ainsi, cette étude montre que la Cycline B1 est un antigène de tumeur caractérisé par un profil singulier de réponses immunitaires, et confirme le potentiel vaccinal de cette protéine pour l’élaboration d’un vaccin anti-Cancer. / Many tumor antigens have been identified since the discovery of the first human antigen about twenty years ago, and some of them have been used as targets for the development of therapeutic cancer vaccines. However, most of the time, the results of clinical trials designed to assess the efficacy of these vaccines proved to be disappointing. Thus, it is still necessary to identify new tumor antigens able to induce strong and long-Lasting anti-Tumor responses that could be used as targets for cancer vaccine. Cyclin B1, an endogenous protein involved in cell cycle regulation, is one of the tumor antigens which are currently considered as potential targets for a cancer vaccine. Usually expressed transiently in healthy dividing cells, this protein is overexpressed in numerous tumors and is necessary for tumor development. Moreover, Cyclin B1 specific spontaneaous immune responses have been observed in cancer patients. My PhD work aimed at characterizing the response of CD4+ T cells, which play a major role in anti-Tumor immune responses, specific to human Cyclin B1 both in healthy individuals and cancer patients. We showed that, in healthy individuals, there exists two pre-Existing Cyclin B1 specific CD4+ T cell populations, namely naive CD4+ T cells and memory CD4+ T cells, the latter lymphocyte population being also found in cancer patients. Multiple CD4+ T cell epitopes have been identified in this protein, and were differently recognized by these two CD4+ T cell populations. Besides, anti-Cyclin B1 IgG antibodies have been detected both in healthy individuals and in cancer patients, without significant differences in antibody levels between these two groups of donors. Therefore, this work shows that Cyclin B1 is a tumor antigen characterized by a singular pattern of immune responses, and confirms the potential of this protein as a target for a cancer vaccine.

Mammalian oocytes undergoing meiotic maturation are transcriptionally silent and gene expression is therefore regulated at the level of translation. One of the well established mechanisms employed in translational regulation of maternal mRNAs in oocytes is cytoplasmic polyadenylation. This process is generally controlled by phosphorylation and activation of cytoplasmic polyadenylation element binding protein (CPEB). The aim of this thesis is to determine the role of mitogen-activated protein kinase (MAPK) in regulation of CPEB-mediated cytoplasmic polyadenylation in maturing mouse and porcine oocytes. For this purpose, MAPK activity was inhibited using its specific inhibitor, GDC-0994 and the effect of MAPK inhibition on cyclin B1 mRNA polyadenylation was monitored. In mouse oocytes, MAPK inhibition impaired neither cyclin B1 mRNA polyadenylation nor its translation and MAPK is thus unlikely to be involved in regulation of cytoplasmic polyadenylation in this species. Based on the results of experiments performed using porcine oocytes, the possible role of MAPK in CPEB-mediated cytoplasmic polyadenylation can neither be confirmed nor ruled out. Keywords: cytoplasmic polyadenylation, mouse oocyte, porcine oocyte, mitogen-activated protein kinase (MAPK), cyclin B1, GDC-0994 inhibitor

Made available in DSpace on 2014-07-29T15:21:56Z (GMT). No. of bitstreams: 1 DIS J V S FILHO 2006.pdf: 804840 bytes, checksum: 74be1a5db70d292dc48c7621acb661f3 (MD5) Previous issue date: 2006-11-27 / Squamous cell carcinoma (SCC) is the most common malignant neoplasm of the bucal cavity, and one of its variants is verrucous carcinoma (VC), of low degree malignancy. The diagnosis of VC is difficult from the clinical as well as from the histopathological point of view, and an effective diagnosis is vital when deciding on the treatment and prognosis of this tumor. The aim of this research was to evaluate cell proliferation and investigate the presence of HPV in spindle cell carcinoma of the mouth so as to check for possible differences in the aetiopathogenesis and biological behavior of these lesions. Forty-seven samples were selected and divided as follows: 39 SCCs, 8 VCs and 9 control (CT). Cell proliferation was qualitatively evaluated according to the location of the expression of the immunomarker in the cell and epithelium layers and by quantitatively considering the percentage of positive cells expressed. The analysis of HPV+ carcinomas was undertaken by means of the polymerase chain reaction (PCR), having GP5+/6+ as primers for identification of the virus. The qualitative analysis showed that the immunomarking in the VC as well as in the control group was concentrated mainly in the basal and parabasal layers and the counting of the positive cells at the base of the epithelium showed a significant statistical difference in the expressions of all three markers (p<0,05). The quantitative analysis of the cell proliferation markers was calculated by means of the Mann-Whitney and Kruskal Wallis tests and through the Pearson and Spermans correlation. They pointed to differences between the SCC and VC groups for the PCNA and cyclin B1 markers (p<0,05). On considering the three groups, it was proved that there was a positive correlation between Ki67 and the cyclin B1 (r=0,56) but not between the PCNA and the Ki67. The PCNA immunomarking was greater in the control group (average=100%), and the Ki67 showed itself to be effective as a proliferation cell marker although it showed no significant difference between the carcinoma variants. Whereas the cyclin B1 showed a significant difference in the comparison between the SCC and the VC groups (p<0,05), and a positive correlation to the extent that the histological grading of the malignancy (WHO model) of the carcinomas increased (r=0,44). All tumor samples were negative for HPV. Although the lesions showed different biological behaviors, the cell proliferation index in both types of mouth carcinoma was higher than in the control group, as shown by the analysis of the Ki67 and cyclin B1 markers. On considering the total sample of carcinomas, independently of the tumor variety, cyclin B1 showed a positive correlation with the histological degree of malignancy according to WHO. There is a need for further study to be carried out in the field of cell proliferation and detection of HPV especially with regard to VC, because it is a rare variant of SCC. / O carcinoma espinocelular (CEC) é a neoplasia maligna mais comum na cavidade bucal, e uma de suas variantes é o carcinoma verrucoso (CV), considerado de baixo grau de malignidade. O diagnóstico do CV é difícil, tanto do ponto de vista clínico quanto histopatológico e um efetivo diagnóstico é fundamental para estabelecer o tratamento e o prognóstico desse tumor. Neste estudo foi avaliada a proliferação celular e investigada a presença de HPV em carcinomas espinocelulares de boca com intuito de verificar possíveis diferenças na etiopatogênese e comportamento biológico destas lesões. Foram selecionadas 47 amostras de CEC assim distribuídas: 39 CECs, 8 CVs e 9 controles (CT). A proliferação celular foi avaliada qualitativamente de acordo com a localização da expressão do imunomarcador na célula e nas camadas do epitélio e quantitativamente considerando o percentual de células positivas expressas. A análise de carcinomas HPV+ foi realizada por meio da reação em cadeia da polimerase (PCR), tendo como primers GP5+/6+ na identificação do vírus. A análise qualitativa revelou que a imunomarcação tanto no CV como no controle concentrava se principalmente nas camadas basal e parabasal e a contagem das células positivas na base do epitélio mostraram diferença estatisticamente significativa na expressão dos três marcadores (p<0,05). A análise quantitativa dos marcadores de proliferação celular foi calculada pelos testes estatísticos Mann-Whitney, Kruskal Wallis, correlação de Pearson e Spermans, que revelaram diferenças entre o grupo CEC e CV para os marcadores PCNA e ciclina B1 (p<0,05). Considerando os três grupos, verificou-se correlação positiva entre Ki67 e a ciclina B1 (r=0,56) e inexistência de correlação entre o PCNA e Ki67. A imunomarcação do PCNA foi maior no grupo controle (média=100%), e o Ki67, mostrou-se efetivo como marcador de proliferação celular, entretanto, não mostrou diferença significativa entre as variantes de carcinomas. Já a ciclina B1 apresentou diferença significativa na comparação entre o grupo CEC e o grupo CV (p<0,05) e correlação positiva na medida em que a gradação histológica de malignidade (padrão OMS) dos carcinomas aumentava (r=0,44). Todas as amostras de tumores foram negativas para o HPV. Embora as lesões apresentem comportamento biológico diferente, o índice de proliferação celular nos dois tipos de carcinomas de boca mostrou ser superior ao do grupo controle, por meio da análise dos marcadores Ki67 e ciclina B1. Quando considerada a amostra total de carcinomas, independente da variante tumoral, a ciclina B1 mostrou correlação positiva com o grau histológico de malignidade segundo a OMS. Há necessidade que mais estudos possam ser empreendidos na área de proliferação celular e detecção de HPV em especial com relação ao CV, por se tratar de uma variante rara do CEC.